Finned heat exchanger



Nov. 18, 1969 3,478,821

W. FIENI FINNED HEAT EXCHANGER Filed Jan. 9, 196'? 2 Sheets-Sheet 1 Walter F/crll INV NT 9 E OR LL. b

Nov. 18, 1969 W. FIENI 3,478,821

FINNED HEAT EXGHANGER Filed Jan. 9, 1967 .2 Sheets-Sheet 2 Fig.6 7105 Fig.7 9 Fig.8 Fig.9

Walter F/tn/ aim 5mm f o o o I by, 154 153 155 110 \102 gwik United States Patent US. Cl. 165-182 Claims ABSTRACT OF THE DISCLOSURE A finned-duct heat exchanger in which each fin is provided with a pair of spaced-apart holes and is connectable with an adjacent fin to define the ducts with the corresponding aligned holes. In addition, each fin, of rectangular configuration, is formed between the holes with a slot extending rectilinearly over at least the major part of the width of the fin, the slots being aligned to define an insulating partition between the ducts. The partition lies in a plane perpendicular to the fins but parallel to the ducts and has a width (equal to the length of the slots) which exceeds the widths of the ducts.

'The invention relates to a finned-duct heat exchanger.

It is an object of the invention to provide a finned-duct heat exchanger which enables different thermal actions to obtain in various zones and which can thus meet conditions of use which have hitherto only been satisfied by a plurality of heat exchangers.

It is a further object of the invention to provide such an exchanger which is simple and economical to produce.

In general, it is an object of the invention to provide a finned-duct heat exchanger which may be used with advantage in the air-conditioning of motor vehicles.

It is a further object of the invention to provide such a heat exchanger, whose mechanical strength is high and which, nevertheless, has a low weight.

It is yet a further object of the invention to provide a heat exchanger adapted to ensure, if necessary, exceptionally intense heat transfer.

According to the invention, the heat exchanger or air heater comprises at least two separate circuits for the circulation of air-conditioning fluids or primary fluids at different temperatures, wherein one and the same set f fins ensures the function of heat transfer with a fluid to be air-conditioned or secondary fluid, for example the ambient air, means being provided to afford thermal insulation between the portions of the fins associated with the first circuit and the portion-s of the fins associated with the second circuit.

It relates in particular to a structure wherein the thermal insulation between the portions of fins isobtained by the actual formation of the fins and, in this connection, to a form of construction characterized in that the two portions of a fin are thermally separated by an air gap formed by a flanged or split aperture.

The interfitting of thesli'ts in the fins defines a sheet of thermal insulation between two sheets of air subjected to the actions of the portions of the fins traversed respectively by the one fluid circuit and by the other.

3,478,821 Patented Nov. 18, 1969 In the following description, given by way of example, reference is made to the accompanying drawing in which:

FIGURE 1 is a view in front elevation of a fin according to the invention;

FIGURE 2 is a view in section along the line 22 of FIGURE 1;

FIGURE 3 is a view partially in section, on a larger scale, showing the assembly of adjacent fins;

FIGURE 4 is a diagrammatic view of an exchanger comprising fins according to the invention;

FIGURE 5 is a view corresponding to FIGURE 1, but for a modification;

FIGURE 6 is a view in elevation of a fin forming part of a heat exchanger according to the invention, but for another form of construction;

FIGURE 7 is a view in section along the line 77 of FIGURE 6;

FIGURE 8 is a view illustrating one stage of production of a fin for one embodiment;

FIGURE 9 is a view in section on the line 99 of FIGURE 8;

FIGURE 10 is a view of the fin represented in FIG- URE 8, when completed;

FIGURE 11 is a view in section on the line 1111 of FIGURE 10;

FIGURE 12 is a partial view, on a larger scale, illustrating the fitting together of fins;

FIGURE 13 is a similar view to FIGURE 8 but for another form of construct-ion;

FIGURE 14 is a view of the finished fin shown in FIGURE 13;

FIGURE 15 is a partial view of a fin as shown in FIGURE '14, in perspective;

FIGURE 16 is a similar view to FIGURES 8 and 13 but for yet another form of construction;

FIGURE 17 is a view in section of the fin illustrated in FIGURE 16, when completed; I

FIGURE 18 is a view of a fin for another form of construction for a heat exchanger according to the invention; and 7 FIGURE 19 is a general view of fins but yet for another form of construction.

A fin 10 according to the invention has, in the form of construction illustrated, an outline of substantially rectangular shape with two long sides 11 and 12 which are the vertical sides (in FIGURE 1) and two short sides 13 and 14. The horizontal sides (in the FIGURES l3 and 14) are adapted to form rims or bent portions 15 and 16 respectively. Two holes 17 and 18 are provided for the passage of tubes 19 and 20 forming ducts for the circulation of air-conditioning fluids. For the connection to said tubes, the holes 17 and 18 are bounded by folded edges or flanges 21 and 22, respectively. The assembly between the tubes and fins is obtained in known manner, for ex ample by expansion of the tubes by means of a liquid at high pressure or by means of bulbous ends. According to a modification, the passages for the circulation offluids can be obtained by fitting edges, of a suitable width surrounding the holes, one inside the other, and applying a sealing edge, in accordance with an arrangement known per se; the tubes 19 and 20 are here omitted.

According to the invention, the fin 10 is divided thermally into two portions 23 and 24 by a central aperture 25, in the form of an elongated rectangle, the major dimension of which is parallel to the horizontal sides 13 and 14 (in FIGURE 1) and the round-ed ends 26 and 27 of which are close to the edges 11 and 12 with which they define narrow strips 28 and 29. Thus the rectangle extends beyond the diameters of holes 17 and 18 and practically the entire width of the fin. The aperture 25'15 substantially in the form of a frustum of a pyramid and is bounded by converging oblique faces of great length 30 and 31. The internal surfaces 34 and 35 (FIGURE 3) of the faces 30 and 31 form part of the face 36 of the fin which may be called the recto, while the outside surfaces 37 and 38 form part of the other face 39 or verso. I

Because of their truncated pyramidal sahpe, the truncated pyramidal slots 40 in adjacent fins (10, 10', can fit one inside the other, the surfaces of the recto of one fin cooperating with the surfaces of the verso of the adjacent fin as shown in FIGURE 3, thus forming a passage 41 enclosing a sheet of air which is thus interposed between the region adjacent to the upper halves 23 of the fins and the region adjacent to the lower halves 24 of the fins.

The resilient fitting one inside the other of substantially cylindrical slits or piercings 42, which are disposed along a peripheral outline as shown in FIGURE 1, contributes in known manner to the relative location of the fins.

A fin according to the invention can be obtained in an extremely simple manner by means of a limited number of operations and even in a single operation, the slits or piercings 42, slits 40, flanges 21, 22 and rims and 16 being obtained by die-stamping of a sheet metal such as is currently used for the manufacture of fins of heat exchangers.

The assembly of the fins 10 with the tubes 19 and and their assembly together are obtained just as easily as that of conventional fins equipping a single conventional heat-exchanger tube.

When a flow of air F sweeps the exchanger according to the invention, transversely to the tubes 19 and 20, as indicated by the arrows in FIGURE 1, the upper portion of the outgoing flow or partial flow F, has been influenced by the upper halves 23 of the fins and the lower portion of the outgoing flow or partial flow F has been influenced by the lower halves 24 of the fins. Said halves 23 and 24 are respectively at temperatures which correspond to those of the fluid circulating in the tubes 19 and 20 which passes through them in such a manner that, in view of the thermal insulation afforded by the sheet of air in the passage 42 and the narrowness of the bridges 28, 29, the flows F and F are comparable, from the point of view of their temperature, to those which would be obtained by the passage of the incoming flow F through two different exchangers comprising the one the tube 19 equipped with the fins associated therewith, and the other the tube 20 equipped with other fins, mechanically separate from said first fins. The manufacture of such exchangers would be more complicated and more expensive than that of the single double-acting exchanger according to the invention.

The pipes 19 and 20 may be connected to different sources of thermal fluid by flow-regulating means (represented diagrammatically in FIG. 4) if necessary. They may also be connected to a single source but with the interposition of a measuring cock. For example, starting from its closed position, said cock may ensure the progressive supply of the pipe 20 with air-conditioning fluid during a first period, the pipe 19 not being fed, then, during a second period, it may control the supply of both the pipes 20 and 19, the supplies being adjustable progressively in the course of one period and the other.

The partial flows F and F may be conveyed toward the utilization point by any appropriate means. By way of example, FIGURE 4 shows a box 50, adjacent to the actual exchanger, at its output side, which thus receives,

in its upper half, the partial flow F and, in its lower half, the partial flow F This box comprises an upper flap 51 which is adjustable and allows the circulation of the flow F to be controlled, and a lower flap 52, permitting the circulation of the flow F 2 to be controlled.

FIGURE 5 shows a modification of a fin, 60, according to the invention, in which the holes 61 and 62, provided for the passage of the air-conditioning fluids, are offset in relation to the center line 63 of the fin in such a manner as to be closer to the edge 64 on which the flow F acts first than to the opposite edge 65, in accordance with an arrangement known per se.

According to one form of construction, each fluid circuit may comprise a plurality of tubes.

The invention provides that the number of fluid circuits may be greater than two, the portions of the fins associated with one circuit beingthermally insulated from the other portions, as defined above.

In another embodiment, a fin according to the invention has holes 101 and 102 (FIGURES 6 and 7), surrounded by a flange 103, 104 for the passage of the pipes for the circulation of primary fluids, for example heating fluids. In a modification, the passages for the circulation of fluids are obtained by fitting flanges 103-104 one inside the other. The thickness of the metal foil constituting the fin may be of the order of of a millimetre. The holes 101 and 102 are preferably offset in relation to the central vertical plane 103. The piercings 106 contribute to a satisfactory location.

According to the invention, a deep slot 107, substantially perpendicular to the plane 105, is present in the fin, opens onto the edge 108 of the latter, and has its other end 109 at a relatively short distance from the opposite edge 110, with which it forms a web or narrow strip 111. Said slot 107 thus defines two halves 112 and 113 of a fin which are in heat-conducting communication only through the fiat web 111 of relatively thin section and through a substantially semicylindrical portion 92 connecting the lips 90 and 91 which form a border around the slot 107 at one face of the fin.

The slot 107 may be obtained by forming a central slit 114 (FIGURE 8) in the fin 100, from the edge 108 to a point 115 adjacent to the side 110, and a small slit 116 at each side of the slit 114 perpendicular thereto. Thus two strips 117 and 118 (FIGURES 10 and 11) can be bent along the lines 119 and 120. The two halves of the fin thus produced are in heat-conducting communication only through a flat web bounded by the edge and the slit 116.

When the fins are mounted on the tubes 121 and 122 (FIGURE 11) by threading the tubes through the fin holes, 101 and 102, respectively, and are rigidly connected to said tubes by known means, or when the passages for the circulation of primary fluids are obtained by fitting flanges 103-104 one inside the other, the strips 117 and 118 interfit as seen in FIGURE 12, thus forming between the upper halves 112 and the lower halves 113 of the fins a substantially flat gap 123, bounded at its upper face by the strips 117 and at its lower face by the strips 118, the inlet face of the gap 123 being largely open exctpt for the very thin edges of the fins and the outlet face being completely open.

The air to be conditioned reaches the heat exchanger equipped with fins according to the invention in accordance with the stream F, and sweeps over the upper halves 112 of the fins and the lower halves 113. If the fluids circulating in the pipes 121 and 122, or in the passages formed by the interen'gaging flanges 103, 104 are at different temperatures, the halves 112 and 113 of the fins are at different temperatures and the air leaves the exchanger in accordance with two streams F and F whose temperatures are substantially as different as if th pipe or passage 121 are equipped with a first set of fins and the pipe or passage 122 were equipped with a second set of fins, completely separate from the previous set.

The webs 111 afford only a very slight conduction between the halves 112 and 113 and the sheet of air circulating in the gap 123 contributes to the satisfactory thermal insulation of hte halves of fins in relation to one another.

With a heat exchanger comprising the set of fins according to the invention, it is possible to obtain streams F and F responding to the conditions which arise in the air-conditioning of a vehicle: for example the stream F is heated while the stream F is not, or, under other circumstances, the stream F is heated to a higher temperature than the stream F Reference will now be made to FIGURES 13 to 15. In this form of construction of the fins, the central cutting and folding operation is preceded by a cutting operation, namely of a circle 130 having a diameter at least equal to the height of the gap which it is desired to form. The cutting is then efiected along the slit 131, then the folding proceeds along the lines 132 and 133 to obtain rims or lips 134 and 135; the fitting together of said upper and lower rims, during the assembly of the fins, defining a gap to limit the circulation of heat or to promote insulation between the lower and upper halves of the fins. The cutting out of the circle 130 facilitates the shaping of the rims or lips and, moreover, ensures a precise location of the end 136 of the slot 137.

Reference will now be be made to FIGURES l6 and 17. In order to manufacture this fin, two circles 138 and 139 are first cut out equidistant from the sides 110 and 108 and then, after cutting along the slit 140, the folding is effected along the lines 141 and 142, thus enabling flanges or lips 143 and 144 to be obtained. The opening 145, bounded by the lips 143 and 144 determines the two halves of the fins 146 and 147 connected to one another only by narrow webs 148 and 149 which may be of small dimensions because of the precise location ensured by the preliminary cutting out of the circles 138 and 139.

Reference will now be made to FIGURE 18. In the exchanger according to this form of construction, the thermally insulating gap is provided with a plate 150 of cardboard or the like which is introduced through an aperture 151 which is entirely open. Not only does the plate 150 act as thermal insulation between the lower half and the upper half of the exchanger but, moreover, it constitutes a member of mechanical structure which reinforces the whole unit and enables the width of the single web152 connecting the upper half 122 of the fin with the lower half 113 to be kept relatively small.

The invention likewise relates to a heat exchanger comprising two distinct circuits for the circulation of primary fluids at different temperatures and, moreover, a third circuit in which the same fluid may circulate as that circulating in one of the two previous ones.

In one embodiment of such an exchanger, one and the same L-shaped fin is threaded by its holes on to the pipes in which the primary fluids are circulating. In a modification, the passages for the circulation of fluid are obtained by interengagement of the flanges surrounding the holes formed in the fin.

In another form of construction, the heat exchanger comprises (FIGURE 19) two pipes or passages 121 and 122 into which are threaded the fins 100 by their holes 101 and 102 and, in addition, on a third pipe or passage 153, fins 154 the height of which is substantially that of the fin halves 113 and which are preferably obtained from fins 100. The fins 154 are in effect extensions of the fin halves 113, the edges 155 of the fins 154 being in contact with the sides or edges 110 of the lower fin halves 113. The pipe 153 preferably has its ends mounted in the same water compartments as the pipe 122. An installation such as that shown in this embodiment is particularly well adapted for the air-conditioning of motor vehicles intended to travel in regions with severe winters. In this case, hot fluids pass through the tubes 153 and 122.

I claim:

1. In a finned-duct heat exchanger in which a multiplicity of substantially similar fins are stacked to form fluid paths, the improvement wherein said fins are each provided with at least a pair of spaced-apart circular holes and are aligned so that the corresponding holes of each pair define a, pair of ducts for at least one heat-exchange fluid, each of said fins being generally rectangular and formed with an elongated narrow slot extending across substantially the midsection of the fin transverse to the longitudinal edges thereof and between the respective holes and subdividing each fin into a pair of fin sections connected only by a zone of limited width beyond the slot, the circular holes having centers lying in a common plane perpendicular to the plane of the respective fin and the slot thereof, the slots of each of said fins being bounded by a peripheral flange engaging an adjacent fin aligned therewith whereby said flanges define between said ducts a generally planar partition parallel thereto and lying perpendicularly to said fins, said slots being open over the entire area bounded by each said flange and having lengths greater than the diameters of said holes.

2. The improvement defined in claim 1 wherein said flanges define an at least partially enclosed flat duct containing a stationary body of air.

3. The improvement defined in claim 1 wherein said flanges define an at least partially enclosed flat duct, said heat exchanger further comprising a body of a solid insulating material received in the duct defined by said flanges.

4. The improvement defined in claim 1 wherein said holes of each fin are bounded by respective flanges extending from the fin codirectionally with the flange surrounding the respective slot and engaging an adjacent fin aligned therewith.

5. The improvement defined in claim 1, further comprising means along the periphery of each fin engageable with complementary means along the periphery of an adjacent fin for enabling assembly of the aligned fins.

6. The improvement defined in claim 4 wherein said holes of each fin are spaced inwardly from the longitudinal sides of the fins by different distances.

7. The improvement defined in claim 6 wherein said slot opens at one of said longitudinal sides but terminates short of the other longitudinal side.

8. A finned-duct heat exchanger, comprising a multiplicity of mutually parallel aligned generally rectangular and similar fins each having a recto and a verso side, each of said fins being formed with a pair of spaced-apart circular holes bordered by respective frustoconical flanges projecting at the recto side of each fin from the plane thereof and engaging the verso side of an adjacent fin whereby said fins and their engaging flanges define a pair of ducts extending parallel to one another through the corresponding holes, each of said fins being further provided with a respective generally rectangular narrow slot between the respective holes and flanked by a peripheral lip projecting integrally from the fin at its recto side and engaging the corresponding verso side of the adjacent fin whereby said lips define a generally fiat hollow partition between said ducts and parallel thereto but perpendicular to said planes of said fins, said slots having a length exceeding the diameter of said holes whereby said partition has a width exceeding that of said ducts, said slots subdividing each of said fins into a pair of sections in thermally-conductive connection over at most a narrow zone.

9. The heat exchanger defined in claim 8, further comprising respective pipes received in said holes and in heattransferring relationship with said fins.

7 10. The heat exchanger defined in claim 8 wherein said partition is provided with an insulating-mass in the form of a cardboard strip.

References Cited UNITED STATES PATENTS 1,863,586 6/1932 Wilke 165-135 1,935,332 11/1933 Quarnstrom 165151 2,983,483 5/1961 Modine 165-151 8 2,602,650 7/1952 Marcotte 165-182 X 3,354,949 11/1957 DeCastelet 165181 FOREIGN PATENTS 1,038,556 8/1966 Great Britain.

ROBERT A. OLEARY, Primary Examiner THEOPHIL W. STREULE, Assistant Examiner US. Cl. X.R. 

